舌平目肉腫。病理組織学的症例報告

Lingual Leiomyosarcoma: A Histopathological Case Report.

抄録

平滑筋肉腫は，平滑筋細胞から発生するまれな悪性間葉系新生物である。平滑筋肉腫は，女性の生殖器，消化管，皮下組織などに好発部位があるが，頭頸部には平滑筋組織が少ないためか，まれな存在である。本症例は60歳男性で，右側舌側縁中央1/3に緩徐に増大する無痛性腫瘤と1x1.5cmの限局性潰瘍を有していた。肉眼的切除後，病理組織学的に多形紡錘細胞，一部は奇妙な核と豊富な病理学的分裂活性を有し，束状に増殖する傾向が認められた。口腔扁平上皮癌の人口学的特徴と危険因子を有していたことから，紡錘形（肉腫型）腫瘍が疑われ，幅広い抗体セットを用いた免疫組織化学的手法により組織遺伝学的グループの証明が行われた。腫瘍はpan-cytokeratinとdesmin陰性，caldesmon限局性陽性，平滑筋アクチン陽性であったため，舌の多形平滑筋肉腫と診断した。

Leiomyosarcomas are rare malignant mesenchymal neoplasms originating from smooth muscle cells. Although leiomyosarcoma is commonly located in the female reproductive system, gastrointestinal tract, and subcutaneous tissues, it is a rare entry in the head and neck area, probably due to the scarcity of smooth muscle tissue in this topographical region. Herein we present a histopathological case report of a 60-year-old male with a slow-growing painless mass on the middle third of the right lateral lingual margin, with focal ulceration measuring 1x1.5cm. After gross excision, histopathology revealed pleomorphic spindle cells, some with bizarre nuclei and abundant pathological mitotic activity with a tendency to grow in a fascicular pattern. As the patient had the demographic characteristic and risk factors for oral cavity squamous cell carcinoma, a spindle-shaped variety (sarcomatoid) variety was suspected, and immunohistochemistry with a broad set of antibodies was used to prove the histogenetic group of the tumor. As the tumor was pan-cytokeratin and desmin negative, focally positive for caldesmon, and positive for smooth muscle actin, the diagnosis of pleomorphic leiomyosarcoma of the tongue was established.